The present invention relates to a suspension for disk drive incorporated in an information processing apparatus, such as a personal computer, and a manufacturing method therefor.
A hard disk drive (HDD) includes a carriage that can turn around a shaft. The carriage is turned around the shaft by means of a positioning motor. The carriage is provided with a plurality of arms, suspensions arranged on the respective distal end portions of the arms, heads attached individually to the suspensions, etc. Each suspension comprises a load beam formed of a precision thin plate spring, a flexure formed of a very thin plate spring that is fixed to the distal end portion of the load beam by laser welding or the like, and a base plate fixed to the proximal portion of the load beam by laser welding or the like. The reverse side of the base plate is fixed to a suspension mounting surface of each arm.
In some cases, a load beam chain blank and a flexure chain blank are used in a process for manufacturing the suspensions. The load beam chain blank is obtained by forming a half-finished plate, having a plurality of load beams arranged in a line, by etching or the like and then press-molding the half-finished plate. The flexure chain blank is obtained by forming a half-finished plate, having a plurality of flexures arranged in a line at given pitches, by etching or the like and then press-molding the half-finished plate. On the other hand, the base plates are separately formed by press molding. In an assembly process, these base plates and the flexure chain blank are welded to predetermined portions of the load beam chain blank. Thereafter, useless portions (scrap portions) of the load beam chain blank and the flexure chain blank are cut off. Thus, independent suspensions are completed.
As described above, the base plates used in the conventional suspension manufacturing process are independent of one another. Therefore, the individual base plates are supplied as single parts to predetermined positions on the load beam chain blank, and are independently positioned by means of separate jigs. In this case, variation of the positioning jigs in workmanship, as well as variation of the base plates in working accuracy, may worsen the accuracy of the respective mounting positions of the base plates with respect to the load beams. Since the base plates are designed to be positioned as single parts on the jigs, moreover, the construction of the jigs is inevitably complicated. If the assembly process is automated, furthermore, the supply of the individual base plates requires use of a complicated base plate feeder.
As each base plate is formed by press molding, a xe2x80x9cburrxe2x80x9d is formed on the shear surface of the plate. Barreling or mechanical polishing operation is carried out to remove this burr. In consideration of the shape accuracy of the base plates and the stability of surface conditions, however, it is to be desired that the plates should be deburred by electropolishing. If the base plates are formed as single parts, however, it is hard to provide the base plates with electrodes for electropolishing.
To cope with these problems, an attempt has been made to handle the base plates in the form of a base plate chain blank in the suspension manufacturing process. The base plate chain blank is a half-finished plate that is composed of a plurality of base plates arranged at given pitches and connected to one another by means of a scrap portion. The base plates of the base plate chain blank are put individually on load beams that are formed on a load beam chain blank. After the load beams and the base plates are welded together, the respective scrap portions of the chain blanks are cut off. However, the following problem is aroused in this case.
In incorporating each suspension into the hard disk drive, each base plate is fixed to the upper or lower surface of an arm, a counterpart for mounting, by means of an adhesive agent, caulking means, etc. If a burr 15 exists on a shear surface that is exposed when the scrap portion is cut off, as shown in FIG. 18, therefore, it inevitably touches a suspension mounting surface 6a of an arm 6. Thereupon, part of a base plate 13 that is fixed to a load beam 11 is lifted to create a gap G between the arm 6 and the base plate 13. Since the base plate 13 will have already been completed by the time the gap G is formed, the burr 15 cannot be removed by barreling or electropolishing.
Accordingly, the object of the present invention is to provide a suspension for a disk drive, capable of avoiding a bad influence exerted by burrs as a scrap portion is cut off from a base plate chain blank.
A manufacturing method according to one aspect of the present invention comprises a process for forming notches along cuttable portions at which a scrap portion of a base plate chain blank, having a plurality of base plates arranged in a line, is to be cut, a process for putting the base plate chain blank in a predetermined position on a load beam chain blank having a plurality of load beams arranged in a line, an assembly process for fixing the base plates to the load beams, individually, and a process for shearing the cuttable portions of the load beam chain blank, thereby cutting off the scrap portion, after the assembly process. The base plate chain blank and the load beam chain blank are used to manufacture a suspension, so that the load beams and the base plates can be easily positioned with respect to one another as they are joined together. Further, the construction of assembly jigs for attaching the load beams to the base plates and the automatic assembly process can be simplified. The base plates can be also electropolished before the scrap portion is separated from the base plate chain blank. Since the scrap portion of the base plate chain blank is sheared at the portions along which the notches are formed, burrs that are formed on cut surfaces are located inside the notches.
Each notch stated herein is a continuous groove that extends along each cuttable portion. The groove may be formed having a cross section in any of various shapes, including the shapes of a V, semicircle, etc., as well as those of tetragons, such as a trapezoid. The shape of the cross section is subject to no restrictions. The notch is formed on at least one of two opposite sides, obverse and reverse, of the base plate chain blank on which a burr is formed.
A suspension for disk drive according to another aspect of the invention comprises a load beam having a proximal portion and a distal end portion of the load beam and fitted with a head, and a base plate fixed to the proximal portion of the load beam and having a scrap shear surface formed on one end thereof and a notch formed along the shear surface so as to contain the shear surface. According to this suspension, a burr, if any, on the shear surface can be located inside the surface extension of the base plate. Thus, the burr can be prevented from interfering with the suspension mounting surface.
The notch may be formed on each of the obverse or reverse sides of the base plate. According to this arrangement, a burr, if any, on either side of the base plate can be prevented from projecting outside the surface extension of the plate surface. If either side of the base plate is put on the suspension mounting surface, the burr can be prevented from interfering with the mounting surface. In the bisymmetrical base plate that need not to be reversible for use, moreover, the notch may be formed only on the obverse or reverse side where the burr is formed. According to this arrangement, the construction of a die for forming the notch can be simplified.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.